If you're looking to retrieve send, delivery, bounce, open, and click information for an email (campaign) or recipient, then I'd actually recommend this endpoint.

While campaignId values can be found in the UI in an email's See details section under Internal HubSpot ID, you won't be able to find create dates and other epoch millisecond timestamps on the front end. Most of the endpoints assume your app is using other endpoints like Get all campaigns and Get campaign data to retrieve the requisite data.